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Comment by jacquesm | Hacker News Reader

Umm, not to be really nasty but did they do a teardown of those sleeves?

You can buy a new phone but if you slip it into a sleeve that size then that still affords plenty of room for a rigged demo. (Sorry, professional deformation at work here.)

What would be far better proof that it works is a simple caloric setup showing how much power is transferred per unit time at which distances and angles from the transducer tile.

Also, where do the optical lasers come in? To find a target to steer beams to using phased arrays of transducers?

If so that would imply only line-of-sight.

edit: so yes, the article confirms line of sight only and very low levels of power delivery

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I wouldn't want to be in that office on 'bring your dog to work' day :-)

I find these stories fascinating not by what they say about the technology but more what they say about the state of education in engineering these days and the ability to believe the impossible is possible. I wonder sometimes if someone told these people "if you can imagine it, you can BUILD it!" and they took that statement literally.

There has been a tremendous amount of work in energy harvesting from ambient sources which is really pretty amazing. There was a fun paper on harvesting sound for energy in 2013 [1]. The key of course is how much energy and at what efficiency.

The CEO's point was that if you can charge anywhere you don't need a full charge, you just top off. It would be interesting to see if it can charge while being used (so net positive charge). In the video at least you can see their device for showing the beam footprint.

I'm also wondering "why talk now?" clearly burned by previous skepticism, why not just wait until you have a fully realized product or are they doing a fund raising round and need some outside validation after their disastrous first go?

[1] http://www.enggjournals.com/ijet/docs/IJET13-05-06-118.pdf

If they think they will be able to raise again at that level without proper due diligence then they are smoking some heavy stuff. Anybody worth their fee will come fully equipped to an on-site job like this and will walk out with the required info: a nice set of data points listing power in and power out at a sequence of increasing distances from the transmitter and if they are thorough they do it with two receivers at a 90' angle from each other, and one run with only one receiver dead center.

If that delivers meaningful power within the typical usage envelope the tech is real. And of course you get to inspect the guts of the box to avoid 'gotchas' of the battery variety.

You can actually buy commercial products that are powered by sound. Sound is actually a pretty great power source for wireless sensor nodes that monitor loud pieces of machinery. Sure, you don't get much power, but for a sensor node you don't need much either. Sometimes sound is the only source of power you can get for such things where it's too dark or parts need to move relative to each making wires difficult. Plus, sometimes you want to monitor the very same vibration that's giving your sensor power.

Now the thing that really gets me is some work I saw on developing a vibration powered sensor for highway bridges. So the best power source they found was a small wind turbine. But when they tried them out on a bridge out in the middle of nowhere, the problem was they were just too much of an entertaining object for people to shoot. So they made this rather large pipe with a magnet on springs inside and were able to harvest energy from the low frequency vibrations of the bridge moving around.

[0]https://www.microgensystems.com/ [1]http://www.ni.com/white-paper/12128/en/

There even was a company that tried to produce windpower based on that principle (windbelt).

I guess that's why they want to make them as roof tiles to cover a whole room with multiples of there and have continuous coverage.

Two points:

1) interference

2) efficiency

Lots of transmitters will interfere with each other, you'll get all kinds of interference patterns at the receiver which will negatively impact efficiency.

And to that point, the second efficiency issue is that you will spend a ton of money to get a trickle of power to those phones, an inductive coupled system in the base of the table would deliver a large multiple because of the tighter coupling (decreased distance, fewer losses because of the medium chosen, electromagnetic coupling is well understood and efficient, acoustic coupling is fraught with all kinds of inefficiencies and hard to make work in a practical setup with useful levels of power).

Is there doubt that it works or that it is practical? I find it unlikely they went through this rigamarole with a case that was actually just a battery case, but this demo hasn't proven that the product will be widely useful as was claimed.

Well, if all it did was light up the 'charging' indicator without delivering meaningful power then yes, it is believable. But if they actually stand by their original claims then I'd open up that box to see what's in it because with the air density being what it is there is no way you're going to deliver that kind of power between two surfaces of the size shown in the article using ultrasound. You're going to get so much interference between the emissions of the various transducers that you'll end up with a very small fraction of the input power on the receiving side.

Yes, there is doubt about whether it works.

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